The increased prevalence of obesity in children is well-documented, and associated with increased risk of diabetes, adult obesity, cardiovascular disease, and psychosocial problems. The prevalence of obesity among Hispanic children is significantly greater, and has increased at a greater rate, as compared to non-Hispanic children. While the factors contributing to the increased prevalence of childhood obesity are complex, socio-ecological theory suggests that social, cultural, and built environmental features of schools and neighborhoods may underlie some of the obesity disparities observed in Hispanic and low-income populations. No studies to date have examined how these factors in combination affect child obesity rates using large, population-based samples of Hispanic children. The overall aim of this study is to examine geographic and multilevel influences of neighborhood and school environments on the development of obesity among 24,000 primarily Hispanic (80%), low-income school children (ages 6-9) in El Paso, TX, a metropolitan city on the US-Mexico border. The population data to be used in this study are from the El Paso Independent School District Fitnessgram(R) surveillance dataset (2006-2009), which includes objectively measured body mass index (BMI) and physical fitness assessment gathered on an annual basis by trained school officials for all elementary school children. Obesity will be assessed using body mass index (BMI) and the Centers for Disease Control and Prevention (CDC) normed percentiles for gender and age [13]. Home residence, BMI, and other attribute information from students will be geocoded in ArcGIS(R) v. 9.3 (Redlands, CA), and combined with other spatial data layers on socio-demographic and built environment features at both the neighborhood (census tract) and school level. By using multilevel and Bayesian modeling, we will address the following specific aims: 1) describe the socio-demographic, physical fitness, and geographic patterns associated with the development of obesity in low-income, primarily Hispanic school children in a border community;and 2) determine the contextual contributions of neighborhood and school environments to the development of obesity and low levels of physical fitness in low, income, primarily Hispanic school children in a border community. The results obtained from this study will provide important insight on the modifiable factors within the neighborhood and school environment that contribute to obesity risk and development. These results will also be used to develop project proposals for multilevel interventions that address childhood obesity, particularly among Hispanic children within a border community context. PUBLIC HEALTH RELEVANCE: Childhood obesity is a significant public health concern, particularly in low-income Hispanic communities on the US-Mexico border. The results from this project will identify modifiable characteristics in the neighborhood and school environment that contribute to obesity risk and development. The identification of these modifiable characteristics is critical to developing interventions within schools and neighborhoods that can reduce the rise of obesity, particularly in vulnerable school children at the US-Mexico border.